1. Field of the Invention
This invention relates to a solid lubricant and a sliding member having a sliding surface covered with a dry film formed by applying a solid lubricant.
2. Description of the Related Art
In the related arts of this invention, there has been developed a solid lubricant which is prepared by using molybdenum disulfide (MoS2), a polytetrafluoroethylene resin (PTFE), etc. as a filler and a polyimide, polyamideimide or epoxy resin, etc. as a binder, as disclosed, for example, in the Japanese patent publications such as shown in JP-B-63-5640 or JP 2,577,416.
Also developed is a hard porous carbonaceous material made by burning and carbonizing in a nitrogen gas atmosphere a material prepared by mixing defatted rice bran with a phenol resin, and called RBC (rice bran ceramics), as disclosed in the raid open patent publication JP-A-10-101453.
The solid lubricant is, however, primarily aimed at a reduction of friction and an improved scoring resistance in the initial stage. Even if it may give good initial sliding properties, the wear of the solid lubricant occurring with the passage of time causes the base surface to be exposed and eventually undergo scoring (roughening of the sliding surface) or seizure.
The performance (wear resistance, coefficient of friction, etc.) of the solid lubricant differs markedly with the properties of the constituents of the filler and binder particularly in an oil-free environment. Consideration is, therefore, required for the selection of the constituents of the filler and binder in order to improve the performance of the solid lubricant.